The number of servers connected to communications networks are increasing. Historically servers has been relative a small number of large machines serving a larger number of clients. However, there are variants growing to this structure, with potentially a large number of light servers serving clients. The clients may be client devices handled be single users, but clients may also be large data retrieving systems in data centers or cloud solutions. The servers may be grid connected servers with a perceived infinite energy supply, energy which however is a limited resource on earth. The servers may also be wirelessly connected servers which are supplied from an energy storage located with the server. The energy storage may be a battery, a capacitor, a tank for feed of a fuel cell or generator similar solutions where the energy is provided from a local source. The servers may also be wirelessly connected servers which are supplied from a limited energy supply, for example a solar panel or wind turbine. When an energy storage is exhausted, it may need to be reloaded or replaced. Such replacement may though be a task of various magnitude or complexity, for example depending of the numbers of servers, the location of a server, or if a server for example is located in a human body and may require surgery for replacement of the energy storage.
Cautious energy usage is of interest for any solutions, including grid connected servers. For servers wirelessly connected to a network, with the energy storage located near or within the server, the operational time is limited by the energy storage, before maintenance is required. Therefore preserving the energy is desired.
Recently, it has been discovered that the limitations of an energy storage located with a wirelessly connected server may be used by elements such as criminals or other individuals or organizations with a goal to sabotage. The elements may purposely put a work load on a server, with the goal to drain the energy storage. The element may not get access to the server, but just handling the requests costs the server undesired energy resources. Such attacks may also be known as DoS-attacks, denial-of-service attacks, flood-attacks, or similar. Wireless servers may be quite vulnerable for such attacks, but also grid connected servers may be caused problems.
Therefore, it is a problem to prevent purposely malicious energy drainage of servers, or to prevent attacks with the purpose to drain servers' energy storage, or attacks with purpose to cause an energy overload. Another problem is that drainage of the energy storage in a wirelessly connected server, may limit the operational time, to a shorter time than intended. Another problem with malicious intended requests is that such energy overload may be causing problems with cooling e.g. in a server farm. The servers connected to the communications network are still intended to be enabled to communicate with other units with honest intentions, i.e. another problem is to maintain communication with friendly units but avoid malicious attackers. Yet another problem is where a client may malfunction and uncontrolled starts to transmit requests. If it in such a case is a powerful or centrally located client, or if a server happens to be of sensitive nature, the malfunctioning client may cause severe damage.